[fetch] The empty string is rejected as header values (#115)

Header value definition is updated (#99 and #100) as:
> A value is a byte sequence that matches the field-content token production.
https://fetch.spec.whatwg.org/#concept-header-value

But this change rejects the empty string as header values (as well as whitespace-only header values before normalization), because field-content in RFC 7230 doesn't match the empty string.
According to w3c/web-platform-tests#2045, it seems we expect to accept the empty string and whitespace-only strings as setRequestHeader() etc., so should we modify header value concept to accept the empty string?



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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/fetch/issues/115